propagation

Short definition from Wiktionary

Noun

1. 1
   The multiplication or natural increase in a population.
2. 2
   The dissemination of something to a larger area or greater number.
3. 3
   The dissemination of something to a larger area or greater number: The winning of new converts.
4. 4
   The act of propagating, especially the movement of a wave.
5. 5
   The elongation part of transcription.